Preparation of aromatic hydrocarbons

ABSTRACT

PROCESS FOR ALKYLATING AN AROMATIC HYDROCARBON BY REACTING A HALOALKANE WITH EITHER BENZENE OR AN ALKYL BENZENE AND CONDUCTING THE REACTION IN THE PRESENCE OF AN ALKYLALUMINUM HALIDE CATALYST WITHOUT DELIBERATELY ADDING HEAT TO ELEVATE THE TEMPERATURE OF THE REACTION.

United States Patent Int. Cl. C07c 15/12 U.S. Cl. 260-668 C 11 Claims ABSTRACT OF THE DISCLOSURE Process for alkylating an aromatic hydrocarbon by reacting a haloalkane with either benzene or an alkyl benzene and conducting the reaction in the presence of an alkylaluminum halide catalyst without deliberately adding heat to elevate the temperature of the reaction.

CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of application Ser. No. 813,340, filed Apr. 3, 1969, which is a continuation-in-part of application Ser. No. 568,779, filed July 29, 1966, both of which are now abandoned.

BACKGROUND OF THE INVENTION This invention relates to the preparation of aromatic hydrocarbons through use of aluminum alkyl halides as Friedel-Crafts catalysts. By way of example, this invention concerns a method for forming an w-haloalkylbenzene or a p-alkyl-w-haloalkylbenzene by reacting an cc,w-dihal0- alkane with, respectively, benzene or an alkylbenzene in the presence of a diluent and an aluminum alkyl halide catalyst. Further, this invention concerns a method for forming an a,w-diphenylalkane or an a,w(p,p'-alkyldiphenyl)alkane by reacting an u,w-dihaloalkane with respectively benzene or an alkylbenzene in the presence of an aluminum alkyl halide catalyst. In addition, this invention provides a method for forming a monoalkylbenzene by reacting a monohalalkane with, respectively, benzene or an alkyl benzene in the presence of a diluent and an aluminum alkyl halide catalyst; absence of a diluent leads to the formation of other polyalkylbenzenes. Other alkylation reactions contemplated by the present invention will become apparent from the following description.

The compounds developed by the process of the present invention find use both as scavengers for alkyl lead antiknock agents (see US. Pats. 1,668,022 and 2,398,281) and as pesticides when properly applied as a spray or dusting powder.

The prior art has been beset with two major problems in reactions of the types involved in the present invention, namely, yield of the desired products has been quite low and reaction temperatures have been necessarily quite high, thus increasing the number of undesirable impurities in the product. Prior art reactions have been conducted using conventional Friedel-Crafts catalysts such as, for example, aluminum chloride. Literature references involving such standard 'Friedel-Crafts catalysts report temperature requirements of 70 C. and higher.

A purpose of the present invention is to overcome the above-noted disadvantages of the prior art. More specifically, a purpose of the present invention is to produce high yields of the desired aromatic hydrocarbons while conducting the requisite chemical reactions at economically low temperatures. Further advantages and purposes of the present invention will become apparent in the following description.

Patented Jan. 22, 1974 ice SUMMARY OF THE INVENTION The present invention provides a process for alkylating an aromatic hydrocarbon by reacting a haloalkane with a compound selected from the group consisting of benzene and alkyl benzenes comprising conducting the reaction in the presence of an alkylaluminum halide catalyst and avoiding the deliberate addition of heat to elevate the reaction temperature.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is drawn to several species of alkylation reactions, four of which utilize an a,w-dihal0- alkane as one reactant and either benzene or an alkylbenzene as the other reactant. Two species of the reactions which produce, respectively, an w-haloalkylbenzene when benzene is a reactant and a p-alkyl-w-haloalkylbenzene when an alkylbenzene is reactant, utilize an organic diluent. Another two species of the reactions which produce, respectively, an a,w-diphenylalkane when benzene is a reactant and a,w-(p,p-alkylidphenyl)alkane when an alkylbenzene is a reactant, do not utilize a diluent. Still another two species of the reactions, which employ a monohaloalkane as one reactant and either benzene or an alkylbenzene as the other reactant to produce, respectively, a monoalkylbenzene or polyalkylbenzene, also employ a diluent; absence of the diluent in either of these two reactions leads to the formation of other polyalkylbenzenes. The remaining species of the reactions are similar to the first four reactions with the exception of employing a,w-dihaloalkanes having different halogens or polyhaloalkanes having more than three halogens which are the same or different. All of the reactions employ as a catalyst one or a combination of dialkylaluminum halide and/ or alkylaluminum dihalide.

Preferred reactions are first, the reaction of 1,2-dichloroethane with benzene in the presence of an organic diluent and methylaluminum sesquichloride to produce 3- chloroethylbenzene; second, the reaction of 1,2-dichloroethane with toluene in the presence of an organic diluent and methylaluminum sesquichloride to produce p-methyl- B-chloroethylbenzene; third, the reaction of 1,2-dichloroethane with benzene in the presence of methylaluminum sesquichloride to produce 1,2-diphenylethane; fourth, the reaction of 1,2-dichloroethane with toluene in the presence of methylaluminum sesquichloride to produce 1,2-(p,p'- methyldiphenyl)ethane; fifth, the reaction of methyl chloride with benzene in the presence of methylaluminum sesquichloride and a diluent to produce toluene; and sixth, the reaction of methyl chloride with toluene in the presence of methylaluminum sesquichloride and a diluent to produce 1,4-dimethylbenzene. The order of stating the reactions above does not indicate an order of preference.

The improvement of the present invention flows primarily from the use in alkylation reactions of alkylaluminum halide catalysts, a preferred catalyst being methylaluminum sesquihalide, which is a mixture of dimethylaluminum halide and methylaluminum dihalide. The organoaluminum catalysts employed in this invention include compounds having the formula R,,AlX wherein R represents a hydrocarbon selected from the group consisting of alkyl and aryl radicals, X represents a halogen selected from the group consisting of chlorine, bromine and iodine, and n represents an integer not greater than 3. Thus, the invention contemplates the use of all organoaluminum halides of the type RAlX and R AIX and mixtures ofthe same (e.g. sesquihalides). In compounds of the R AlX type, the R groups may be the same or different, -g- 3) (CzH )AlX. These catalysts cause the above reactions to proceed at a relatively fast rate at comparatively low temperatures which need not exceed room temperatures, and thus, no heating is required in the present invention as is generally required as taught by the prior art. Conventional Friedel-Crafts catalysts, such as are also useful in the practice of the invention. Such haloalkanes preferably have from 1 up to about 20 carbons and preferably up to about 4 carbon atoms. Exemplary are chloroform, brornoform, methylene chloride, methyl chloroform, 1,1,2-trich1oroethane, 1,l,2,2-tetraiodoethane,

aluminum chloride, not only require supplying heat to the 1,l,l,2-tetrabromoethane, 1,1,3-tr1chloropropane, 1,1,4-tr1- reaction but tend to remain in suspension in the reactants iodobutane, 1,1,10-trichlorodecane, chlorobromoethane, thus leading to slow reactions. On the other hand, alkyl- 1-chloro-3-bromo-6-iodohexane, and the like. aluminum halide catalysts are readily soluble in the rc- The present invention also lends itself to a relatively actants and are conducive to fast reactions, good converwide variety of alkylbenzene reactants having from 7 up sions and high yields. The molar ratio of reactants to to about 30 carbon atoms and preferably up to about 10 catalyst may range from about 0.05 to 0.1 to about 5 to carbon atoms; with re c a y includ? one Sal/Q31 0.1; preferably it will range from about 0.1 to 1.0 to about alkyl radicals which are the same or different. Typical 2 to 0.1. In continuous operation processes, the catalysts alkylbenzenes include toluene, ethylbenzene, p-ethylof the present invention may be easily recovered and repr pylbenzene, propylbenzene, butylbenzene, 1sopropy1- cycled for continuing use. benzene, isobutylbenzene and decylbenzene, with a pre- Numerous diluents are suitable for those reactions of ferred alkylbenzene bemg toluene. the present invention which require a diluent. Typical Having thus set forth the present invention, the followorganic diluents are ligroin, nitrobenzene, carbon disulfide, mg examples are presented as being further descriptive hexane, and isooctane. In general, all parafiinic hydroof the present invention, though not as hunting thereof: carbons which arediquid at reaction temperature are suit- EXAMPLE I able. All useful dlluents must be liquid at reaction temperatures and inert to the reactants of the present invend mol of bFnZene was reactfid Wlth mol of tion. Generally, 50 percent to 80 percent by volume of the dIChIPFOethaBe e Presence of {1101 Of y reactant solutionis diluent aluminum sesquichlonde and a hexane diluent at 25 C.

A broad range of monohaloalkanes are useful in some to Produce Predommanfly l3'chloroethylbenzeneof the reactions of the invention. Exemplary are com- EXAMPLE 11 pounds having up to about 20 carbon atoms, e.g., methyl chloride, methyl bromide, ethyl chloride, propyl bromide, i of i g was reactefd 3 of 1: butyl chloride, pentyl bromide, decyl bromide, fi-methyl- 1c (Frost am i t presencoe o moe 0 me yl-chlorodecane, and the like. Preferred haloalkanes have aiummum sesgmchlonde at 25 to Produce a 80 Percent from 2 up to about 4 carbon atoms. Yleld 0 1,2-d1phenylethane.

A comparatively wide variety of a,w-dihaloalkane re- EXAMPLE III actants may be used 1n some of the present invention. one mol of toluene was reacted with 0.2 mol of Typical a,w dihaloalkanes have from 2 up to about 20 dlchloroethane m the presence of 0.1 mol of methylcarbon atoms and include such compounds as 1,2-d1chloroo ethane 1 2 dibromoethane 1 2 diiodoethane 1 2 dichloro aluminum sesquichlorrde and a hexane diluent at 25 C. to roducere mi tl h--hlrot propane, 1,4d1chlorobutane, and 1,2-d1chloro-2-methyl- P p do nan y Pmet Y1 c 0 e hylbenzene propane, 1,5-dichloropentane, 1,8-dibromooctane, 1,10-di- EXAMPLE IV 111 1 110dib 6 thld am l'k c 0Y0 ecane, 3 IOHIO- Y ecalle, an e 1 One mol of toluene was reacted with 0.5 mol of 1,2- Preferred a,w-d1hal oalkanes have from about2 up to about dichlol-oethane in the presence f 0.2 mol f methyl. 4 carbon atoms, with the most preferred a,w-d1haloalkane aluminum sesquichloride at 25 C. to produce prebemg 1,2-d1chloroethane. dominantly 1,2-(p,p'-methy1diphenyl)ethane.

=Polyhaloalkanes other than a,w-dihaloa1kanes havlng The following examples may be carried out under the two or more halogens which may be the same or diiferent 45 listed conditions to yield predominantly the product noted.

Example Temperanumber Reactants Catalyst ture, C. Diluent Product V Benzene plus 1,2-dibromoethane-.. Methylaluruinum sesquibromide- 25 Is00etane fl-Bromoethylbenzene. VI. .do-.- do.- 25 one 1,2-diphenylethane. VII Toluene plus 1,2-dibromoeth n .do-- 25 Hexane p-Methyl-fi-bromoethylhenzena. VIII 1 dn do--. 25 None 1,2-(p,p'-methyldiphenyl)ethane. IX Benzene plus 1,3-dichloropropane- Methylaluminum sesquich10ride. 25 Isooctane-- 'y-Chloropropylbenzene. Y rln 0. 25 None 1,3-diphenylpropane. XI Benzene plus 1,4-dichlor0butane --do 25 Hexane a-chlorobutylbenzene. YTT rln do" 25 None 1,4-diphenylbutane. XIII Etlglylbenzeno plus 1,2-dichloro- ..do 25 Hexane p-Ethyl-B-chloroethylbenzene.

e 3118- XIV dn do" 25 1,2-(p,p-ethyldiphenyl)ethane. XV Prozrfiylbenzene plus 1,2diehloro- --d0 25 p-Propyl-fl-chloroethylbenzene.

6 ane. XVI do .do--- 25 None l,2-(p,p'-propyldiphenyl)ethane. XVII Buglylhenzene plus 1,2-dichlorod0 25 Hexane p-Butyl-fl-ehloroethylbenzene.

6 9.118- XVIII dn do 25 None 1,2-(p,p-butyldiphenyl)ethane. XIX Btlrtsglbenzene plus 1,4-dichloro- ..d0 25 Hexane p-Buty1-4-chl0robutylbemene.

u 9.119. YY rln do--- 25 None l,4-(p,p-butyldiphenyl)butane. XXI Benzene plus 1,10-diiododeeane Decylaluruinum sesquiiodlde 0 Llgroin K-iododecylhenzene XXII Deieylbenzene plus 1,10-dibromo- Decylaluminum dibromide...-. 5 Nitrobenzene. p-Methyl-K-bromodeeylbeuzene.

662K19- XXIII Beanzene plus 1,10-diehlorodo- Deoylaluminum sesquichlorideflur 10 None 1,10-diphenyldodecane.

GUS-I18. XXIV.- Dgcylbenzene plus 1,10-dicl11orod0- Ethylaluminum sesquibromide--- 15 None 1,10(p,p'-decyldiphenyl)decane.

808.116. XXV Benzene plus 1,7-diiodoheptane--- Ethylalmninum diiodide 20 cairib tilnfid n-Iodoheptylbenzene.

S e. XXVI Hgptylbenzene plus 1,7-diehloro- Diethyleluminum chloride 30 Hendecane.- 1,7-(p,p'-hepty1diphenyl)heptane.

ep ane. XXVII-.-. Benzene plus 1,6-dibromohexane Propylaluminum sesquibromide 35 None 1,6-diphenylhexane.

exane. XXVIII Hexylbenzene plus 1,8-dieh1oro- Butylaluminum sesquiehloride 40 ..do 1,8-(p,p-hexyldiphenyl)Octane.

00 311B. XXIX Benzene plus methylchloride Dodecylaluminum dichloride Toluen XXX Benzene plus methylene chloride Methylaluminum sesquichlorid Dipheuylmethane.

Benzene plus ethyl chloride. Ethylaluminum sesquichloride- Ethylbenzene.

XXX XXXII-.. Benzene plus propyl bromide Methylaluminum dibromide Nitrobenzene: Propylbenzeue.

TABLE-Continued Example Temperanumber Reactants Catalyst ture, C. Diluent Product XXXIII Benzene plus butyl iodide Propyleluminum sesquichloride. 5 (leribon Butylbenzene.

XXXIV Benzene plus decyl chloride Octylaluminum dichloride 2 Hexane Decylbenzene. XXXV Decglbenzene plus methyl chlo- Dimethylaluminum chloride 12 Heptane p-Decyl-methylbenzene.

r1 e. XXXVI Toluene plus ethyl chloride Butylaluminum sesquichloride...- 28 Octane p-Methyl-ethylbenzene. XXXVII Etllilslrlbeinzene plus methylene Henldecylaluminum sesquiehlo- 35 None.-." Diethyldiphenylmethane.

c on e. r1 e. XXXVIIL.-- Propglbenzene plus propyl bro- Dodecylaluminum dibromide-. 16 Ligroin p-Propyl-propylbenzene.

m1 e. XXXIX Butglbenzene plus methyl chlo- Methylaluminum sesquichloride... 20 Nitrobenzene. p-Butyl-methylbenzene.

r1 e. XL Decylbenzene plus decyl iodide... Methylaluminum sesquiiodide 25 Hexane p-Decyl-deeylbenzene. XLL- Benzene plus chloroform Methylnluminum sesquichloride-.- Heptane. a,a-Dichlorotoluene.

Benzene plus methylene iodide Ethylaluminum sesquichloride...- 40 Hexane Diphenylmethane. XLIII Benzene plus methyl chloroform Propylaluminmn sesquichloride--- 33 None.. a-Methyl-$-chloro-diphenylmethane.

XLIV Benzene plus 1,1,3,3-tetrabromo- Dipropylaluminum bromide 26 Deeane 1,1,3,3-tetraphenylpropane.

propane. XLVj Beinzene plus 1,1,10,10-tetraiodo- Decylaluminum diiodide Ligroin 1,1,10,10-tetraphenyldeeane.

eeane. Toluene plus chloroform.- Methylaluminum dichloride 8 Nitrobenzenea-Ohloro-di-p-tolymethane. Toluene plus methylene bromide Dimethylaluminum bromide 29 None--. Di-p-tolymethane. Benzene plus chlorobromoethane Ethylalulmnum sesquibromide 1 Isoocta B-Chloroethylbenzene.

XLIX p-Ethyl-n-propylbenzene plus Methylaluminum sesqurehloride.-. 38 Hexane l-methyl--ethyl-n-propylbenmethyl chloride. zone.

What is claimed is:

1. A process for the production of a,w-diphenylalkanes by reacting, in a diluent-tree system and in the presence of an alkylaluminum halide catalyst, an c m-polyhaloalkane and benzene wherein said polyhaloalkane contains from 2 to about carbon atoms and wherein said polyhaloalkane contains halogens selected from the group consisting of chlorine, bromine and iodine.

2. The process of claim 1 wherein said polyhaloalkane is an a,w-dihaloalkane.

3. The process of claim 1 wherein said polyhaloalkane is 1,2-dichloroethane.

4. The process of claim 1 wherein said alkylaluminum halide catalyst is methyaluminum sesquichloride.

5. The process of clim 1 wherein said polyhaloalkane is 1,2-dichloroethane, and wherein said alkylaluminum catalyst is methylaluminum sesquichloride.

6. A process for the production of u,w-(p,p-alkyl-diphenyl)alkane by reacting, in a diluent-free system and in the presence of an alkylaluminum halide catalyst, an 04,0:- polyhaloalkane and an alkylbenzene wherein said polyhaloalkane contains from 2 to about 20 carbon atoms, wherein said polyhaloalkane contains halogens selected from the group consisting of chlorine, bromine and iodine and wherein said alkylbenzene contains from 7 to about 30 carbon atoms.

7. The process of claim 6 wherein said alkylbenzene is toluene.

8. The process of claim 6 wherein said polyhaloalkane is an a,w-dihaloalkane.

UNITED STATES PATENTS References Cited 2,794,822 6/ 1957 Schweitzer 260-668 C 3,301,514 4/1962 Kosmin 260-671 C 3,094,568 6/1963 'Hay et al 260-671 C. 3,277,196 10/1966 Winkler 260-671 P 3,312,748 4/1967 Johnson 260-671 R 2,355,850 8/1944 Driesbech 260-651 HA 2,308,419 1/1943 Heitz et a1 260-651 HA 2,631,172 3/1953 Schmerling 260-651 HA 2,388,428 11/ 1945 Mauity 260-448 A OTHER REFERENCES Schmerling et al., J.A.C.S., 79, pp. 2636-42, May 20, 1957.

CURTIS R. DAVIS, Primary Examiner US. Cl. X.R.

260-651 HA, 671 B, 671 C, 671 P 

